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The behaviour of two-dimensional finite blobs of conducting viscous fluid in a Hele-Shaw cell subject to an electric field is considered. The time-dependent free boundary problem is studied both analytically using the Schwarz function of the free boundary and numerically using a boundary integral method. Various problems are considered, including (i) the behaviour of an initially circular blob of conducting fluid subject to an electric point charge located arbitrarily within the blob, (ii) the delay in cusp formation on the free boundary in sink-driven flow due to a strategically placed electric charge and (iii) the stability of exact steady solutions having both hydrodynamic and electric forcing. [ABSTRACT FROM AUTHOR]

RNA interference ( RNAi) has become a widely used loss-of-function tool in eukaryotes; however, the delivery of double-stranded ( ds)RNA) to the target cells remains a major challenge when exploiting the RNAi-technology. In insects, the efficiency of RNAi is highly species-dependent. Yet, the mechanism of cell entry in insects has only been characterized in a cell line of the fruit fly, Drosophila melanogaster, a species that is well known to be poorly amenable to environmental RNAi. In the present paper, we demonstrate that silencing vacuolar H- ATPase 16 ( vha16) and clathrin heavy chain ( clath), two components of the Clathrin-dependent endocytosis pathway, together with pharmacological inhibition of scavenger receptors with polyinosine and dextran sulphate, can significantly attenuate the highly robust RNAi response in the desert locust, Schistocerca gregaria. [ABSTRACT FROM AUTHOR]

In the last decade, genome sequence data and gene structure information on invertebrate receptors has been greatly expanded by large sequencing projects and cloning studies. This information is of great value for the identification of receptors; however, functional and pharmacological data are necessary for an accurate receptor classification and for practical applications. In insects, an important group of neurotransmitter and neurohormone receptors, for which ample sequence information is available but pharmacological information is missing, are the biogenic amine G protein-coupled receptors ( GPCRs). In the present study, we investigated the sequence information, pharmacology and signalling properties of a 5- HT7-type serotonin receptor from the red flour beetle, Tribolium castaneum ( Trica5- HT7). The receptor encoding cDNA shows considerable sequence similarity with cognate 5- HT7 receptors and phylogenetic analysis also clusters the receptor within this 5- HT receptor group. Real-time reverse transcription PCR demonstrated high expression levels in the brain, indicating the possible importance of this receptor in neural processes. Trica5- HT7 was dose-dependently activated by 5- HT, which induced elevated intracellular cyclic AMP levels but had no effect on calcium signalling. The synthetic agonists, α-methyl 5- HT, 5-methoxytryptamine, 5-carboxamidotryptamine and 8-hydroxy-2-(dipropylamino)tetralin hydrobromide, showed a response, although with a much lower potency and efficacy than 5- HT. Ketanserin and methiothepin were the most potent antagonists. Both showed characteristics of competitive inhibition on Trica5- HT7. The signalling pathway and pharmacological profile offer important information that will facilitate functional and comparative studies of 5- HT receptors in insects and other invertebrates. The pharmacology of invertebrate 5- HT receptors differs considerably from that of vertebrates. The present study may therefore contribute to establishing a more reliable classification of invertebrate 5- HT receptors. [ABSTRACT FROM AUTHOR]